Apparatus and methods for regulated voltage

ABSTRACT

An electronic system according to various aspects of the present invention includes a memory and a supply regulation circuit having a regulated output to provide a selected voltage level. In one embodiment, the supply regulation circuit includes a reference voltage circuit connected to the supply and configured to receive a first voltage and a second voltage and provide a reference voltage and a control circuit connected to the reference voltage and configured to control the regulated voltage according to the reference voltage. The supply regulation circuit also includes an adjustment circuit controlled by the control circuit and configured to adjust the regulated voltage according to the reference voltage. The supply regulation circuit may also include a compensator circuit to provide additional adjustment to the regulated voltage.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application claims priority to application Ser. No. 10/217,665,entitled “Apparatus and Methods for Regulated Voltage,” filed Aug. 12,2002 and is incorporated herein by reference.

FIELD OF INVENTION

The present invention generally relates to electronic circuits.

BACKGROUND OF THE INVENTION

Many electronic systems use multiple voltage levels in the same system,and often in the same component. Electronic systems use various voltagelevels to drive signals and promote particular operating characteristicsfor a circuit. For example, a memory chip may require several differentvoltage levels to operate, such as a main supply voltage, a main supplyground, a bulk voltage, and a negative word line voltage.

Many power supply schemes have been developed for accommodating thedifferent voltage levels. One possible configuration is to minimize thenumber of voltage levels by using identical voltage levels for differentfunctions. For example, a memory may be configured to use the samevoltage level for the bulk voltage V_(BB) and the negative word voltageV_(NEG). Using identical voltage levels for different signals, however,reduces flexibility and tends to inhibit optimal operation.

An alternative solution is to provide a dedicated circuit including acharge pump for each voltage level to provide the requisite power to thesystem. These systems are relatively expensive, however, for eachdedicated circuit in the system requires additional materials,fabrication, testing, chip space, and design. Further, using dedicatedcircuits for each voltage level adds complexity. For example, thevarious voltage level supply circuits may require activation in aselected sequence to avoid latchup problems.

SUMMARY OF THE INVENTION

An electronic system according to various aspects of the presentinvention includes memory and a supply regulation circuit having aregulated output to provide a selected voltage level. In one embodiment,the supply regulation circuit includes a reference voltage circuitconfigured provide a reference voltage. The supply regulation circuitalso includes a control circuit connected to the reference voltage andconfigured to control the regulated voltage according to the referencevoltage. In addition, the supply regulation circuit includes anadjustment circuit controlled by the control circuit and configured toadjust the regulated voltage according to the reference voltage. Thesupply regulation circuit may also include a compensator circuit toprovide additional adjustment or maintenance to the regulated voltage.

BRIEF DESCRIPTION OF THE DRAWING

Aspects of the present invention are disclosed in the non-limitingembodiments described in the specification and the claims, inconjunction with the accompanying figures, wherein like numeralsdesignate like elements:

FIG. 1 is a block diagram of an electronic system according to variousaspects of the present invention;

FIG. 2 is a block diagram of an exemplary supply and a memory system;

FIG. 3 is a block diagram of an exemplary supply regulation circuit;

FIG. 4 is a schematic diagram of an exemplary supply regulation circuit;

FIG. 5 is a schematic diagram of an exemplary reference voltage circuit;

FIG. 6 is a schematic diagram of an exemplary supply regulation circuithaving a compensation circuit including a current source;

FIG. 7 is a schematic diagram of an exemplary supply regulation circuithaving a compensation circuit including a second differential amplifierand an adjustable impedance; and

FIG. 8 is a schematic diagram of an exemplary integrated control circuitand adjustment circuit.

Elements in the figures are illustrated for simplicity and clarity andhave not necessarily been drawn to scale. For example, the dimensions ofsome of the elements in the figures may be exaggerated relative to otherelements to improve understanding of the embodiments of the presentinvention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Various aspects and features of the present invention may be describedin terms of functional components and steps. Such functional componentsand steps may be realized by any number of elements and/or stepsconfigured to perform the specified functions. For example, the presentmethods and apparatus may employ electronic, signaling, and logicelements, like impedances, transistors, operational amplifiers, voltagesupplies, and current sources, which may carry out a variety offunctions in various embodiments, applications, and environments. Inaddition, the present methods and apparatus may be practiced inconjunction with any number of procedures and systems, and the apparatusand methods described are merely exemplary applications for theinvention. Further, the methods and apparatus may employ any appropriatetechniques, conventional or otherwise, for placement, use,manufacturing, and the like.

An electronic system according to various aspects of the presentinvention includes a plurality of components operating in conjunctionwith a supply regulation circuit. The components may comprise anycomponents using a supply regulation circuit, such as multipleintegrated circuits and electrical components on a single board, variouselements in a single integrated circuit, various components of acomputer system, or any other components. For example, referring to FIG.1, an exemplary electronic system 100 suitably comprises a computerhaving a processor 110, a supply 112, and a memory system 114. Theprocessor 110 controls the electronic system 100, such as in accordancewith a program. The processor 110 may comprise any controlling element,for example a conventional central processing unit, such as an IntelPentium processor or an Advanced Micro Devices Athlon processor.

The supply 112 provides power to the various components of theelectronic system 100, including the processor 110 and the memory system114. The supply 112 may comprise any source of power for the electronicsystem 100, such as a conventional electric power supply, a charge pump,and/or other power supplies. In the present embodiment, the supply 112is connected to the processor 110 and is configured to supply at leasttwo voltage levels. Although the present embodiment includes theprocessor 110, the supply 112, and the memory system 114, the electronicsystem 100 may include any suitable components.

The memory system 114 stores information for subsequent retrieval. Thememory system 114 may comprise any appropriate memory, memory system, orstorage device or system. The memory system 114 may comprise, bereplaced by, or be supplemented by any component or system drawing powerfrom the supply 112. The memory system 114 is suitably connected to theprocessor 110 and configured to provide information to the processor110. For example, referring to FIG. 2, the memory system 114 of thepresent embodiment suitably comprises a memory 210 and a supplyregulation circuit 212. The memory 210 comprises any suitable system forstoring data for later retrieval, such as a memory subsystem including amemory controller, multiple memory chips, and associated logic andcircuitry. In the present embodiment, the memory 210 comprises an SDRAM,such as an SDRAM available from Micron Technology, Inc. The memory 210suitably includes multiple word lines and bit lines used to storeinformation at selected addresses in the memory 210.

The supply regulation circuit 212 controls the supply levels to one ormore components of the electronic system 100, such as the memory 210. Inthe present embodiment, the supply regulation circuit 212 is integratedinto the memory 210, though the supply regulation circuit 212 may beintegrated into other components of the memory 210 or implemented as aseparate circuit. The supply regulation circuit 212 according to variousaspects of the present invention provides selected voltage levels to thememory 210. In particular, the supply regulation circuit 212 isconnected to the supply 112 to receive power and may be configured togenerate, monitor, and regulate one or more particular voltages for thememory 210. The supply regulation circuit 212 may comprise any suitablesupply regulation circuit, such as a voltage control circuit, currentcontrol circuit, or any other supply regulation circuit or suitablecombination of circuits.

In the present embodiment, the supply regulation circuit 212 isconfigured to generate a negative word line voltage V_(NEG) to supply anegative signal to one or more word lines of the memory 210. The supplyregulation circuit 212 may be configured in any suitable manner toprovide the negative word line voltage V_(NEG). The supply regulationcircuit 212 may be configured to provide and regulate selected voltagesand/or currents according to any criteria and in any suitable manner.For example, referring to FIG. 3, a supply regulation circuit 212according to various aspects of the present invention is configured toselectively provide at least one regulated voltage and/or current to theword lines of the memory 210. The supply regulation circuit 212 suitablycomprises a reference voltage circuit 310; a control circuit 312; and anadjustment circuit 314. The reference voltage circuit 310 is suitablyconnected to the supply 112 and configured to provide a controlreference voltage. The control circuit 312 is suitably connected to thereference voltage circuit 310 and configured to control the regulatedvoltage according to the control reference voltage. Further, theadjustment circuit 314 is suitably controlled by the control circuit 312and configured to adjust the regulated voltage according to the signalsreceived from the control circuit.

More particularly, the reference voltage circuit 310 generates one ormore control reference voltages, such as a control reference voltage forthe negative word line voltage V_(NEG). In the present embodiment, thecontrol reference voltage may comprise any suitable voltage or othersignal to be used as a target voltage by another component. Thereference voltage circuit 310 may be configured in any suitable mannerto generate the control reference voltages. For example, referring toFIG. 4, the reference voltage circuit 310 is connected to a firstvoltage and a second voltage to generate the control reference voltagebetween the first and second voltages. The reference voltage circuit 310suitably comprises a voltage divider circuit having a first terminalconnected to, for example, a main ground V_(SS) from the supply 112 anda second terminal connected to, for example, a bulk voltage V_(BB), alsosuitably generated by the supply 112. At least two impedances 410, 412form the voltage divider. In the present embodiment, the impedances 410,412 comprise conventional resistors. Alternatively, the impedances 410,412 may comprise variable resistors, resistive-capacitive elements,transistors, or any other appropriate elements for generating thedesired control reference voltage. Further, the first and secondvoltages may be any appropriate voltages or other signals from which thecontrol reference voltage may be derived.

In another embodiment, the reference voltage circuit 310 may beconfigured to generate multiple control reference voltages. For example,referring to FIG. 5, a voltage divider may be configured having multipleimpedances 510 and multiple taps 512 to generate multiple controlreference voltages. The multiple control reference voltages, however,may be generated by any suitable system for generating multiplereference voltages. Any number of control reference voltages may begenerated for use by the memory 210 and/or other components of theelectronic system 100. Further, the reference voltage circuit 310 may beconfigured in any suitable manner to connect the regulated voltage toground or another potential, for example in response to a test mode thatmay require discharging a relatively large load from the memory 210.

In addition, the reference voltage circuit 310 may include a buffer, forexample between the supply 112 and one or more of the supply terminalsof the reference voltage circuit 310. The buffer may be included oromitted according to the configuration of the supply regulation circuit212. For example, if the supply 112 comprises a high impedance node, thebuffer may be included to provide a lower impedance source for thesupply voltage.

The control circuit 312 controls the regulated voltage according to thecontrol reference voltage. In one embodiment, the control circuit 312compares the regulated voltage to at least one of the control referencevoltages. The control circuit 312 also suitably controls the adjustmentcircuit 314, for example by generating a control signal provided to theadjustment circuit 314.

The control circuit 312 may comprise any suitable circuit forcontrolling the adjustment circuit or providing the regulated voltageaccording to the control reference voltage circuit. Referring again toFIG. 4, the control circuit 312 of the present embodiment comprises adifferential amplifier 414 having an inverting input connected to thecontrol reference voltage and a noninverting input connected to theregulated voltage. The differential amplifier 414 generates the controlsignal, such as a differential signal proportional to the differencebetween the control reference voltage and the regulated voltage, whichis suitably provided to the adjustment circuit 314.

Referring to FIG. 8, an alternative embodiment of a control circuit 312provides the regulated voltage directly with an integrated adjustmentcircuit 314. The control circuit 312 provides a signal at the level ofthe control reference voltage to maintain the output voltage at thelevel designated by the control reference voltage. For example, thecontrol circuit 312 suitably comprises a substantially unity (eitherinverting or noninverting) gain amplifier, to drive the adjustmentcircuit 314. In the present embodiment, the control circuit 312 isimplemented as an inverting operational amplifier having a gain ofapproximately 1 or −1. In particular, the operational amplifier has anoninverting input connected to ground and an inverting input connectedto the reference voltage circuit 310 via an input resistor. Theinverting input is also connected to the output of the operationalamplifier via a feedback resistor having a substantially identicalresistance as the input resistor.

The adjustment circuit 314 is controlled by the control circuit 312 andis configured to generate the regulated voltage using another voltageand adjust the regulated voltage according to the control signal. Theadjustment circuit 314 may be configured in any suitable manner togenerate the regulated voltage and adjust the regulated voltageaccording to the control reference voltage. For example, referring againto FIG. 4, the adjustment circuit 314 suitably comprises an adjustableimpedance, such as an n-channel insulated gate transistor 416. Ifappropriate, the transistor 416 may be supplementally implanted to raiseits threshold voltage such that the transistor 416 is off when the gatevoltage is at the lowest voltage supplied by the control circuit, suchas ground V_(SS). The transistor 416 has a control terminal foradjusting the impedance of the transistor, such as a gate, connected tothe control circuit 312 to receive the control signal. A supplyterminal, such as the drain of the transistor 416, is connected to asupply voltage from which the word line supply voltage V_(NEG) is drawn,such as the bulk voltage V_(BB). The regulated voltage is suitablyprovided at the source of the transistor 416. In the present embodiment,the negative word line voltage V_(NEG) voltage level is selectivelyconnected to the word lines of the memory 210. The adjustment circuit314 may thus adjust the regulated voltage V_(NEG) by varying theimpedance of the transistor 416.

In the alternative embodiment, the adjustment circuit 314 may be omittedor integrated into an amplifier 810 (FIG. 8). The amplifier 810 issuitably configured to automatically compensate for changes in currentor voltage at its output to maintain a substantially constant voltage.The adjustment circuit 314 is integrated into the amplifier 810.Accordingly, the output of the amplifier 810 may be used as the outputV_(NEG) of the supply regulation circuit 212.

In operation, the negative word line voltage V_(NEG) is selectivelyconnected to one or more word lines of the memory 210. Consequently, thevoltage applied to the negative word line voltage V_(NEG) varies ascharged word lines are connected to the negative word line voltageV_(NEG) following memory 210 accesses. As the negative word line voltageV_(NEG) changes, the control circuit 312 compares the current negativeword line voltage V_(NEG) to the control reference voltage. If thecurrent negative word line voltage V_(NEG) is too high, the controlcircuit 312 adjusts the control signal, for example to reduce theimpedance of the transistor 416. In particular, the differentialamplifier 414 generates a differential signal having an amplitudecorresponding to the magnitude of the difference between the controlreference voltage and the negative word line voltage V_(NEG). Thedifferential signal is provided to the transistor 416 of the adjustmentcircuit 314, which reduces the impedance of the transistor 416. As aresult, the negative word line voltage V_(NEG) is pulled lower towardsthe bulk voltage V_(BB), thus returning the negative word line voltageV_(NEG) to the proper voltage level. Similarly, if the negative wordline voltage V_(NEG) is too low, the control circuit 312 adjusts thecontrol signal to increase the impedance of the transistor 416. Theadjustable impedance of the transistor 416 tends to drive the negativeword line voltage V_(NEG) towards the control reference voltage, thusmaintaining the desired regulated voltage for, for example, the negativeword line voltage or other desired signal. In embodiments having omittedor integrated adjustment circuits 314, the control circuit 312 adjuststhe output signal of the control circuit 312 to maintain the desiredvoltage according to the control reference voltage.

Thus, a supply regulation circuit 212 according to the presentembodiment provides a negative word line voltage V_(NEG) by maintaininga signal between the bulk voltage V_(BB) and ground. The bulk voltageV_(BB) supply provides all of the required current. The adjustmentcircuit 314 facilitates siphoning any required current from the bulkvoltage V_(BB) supply. Consequently, a single pump of adequate capacitymay supply both the bulk voltage V_(BB) and the negative word linevoltage V_(NEG). In this embodiment, if either load connected to thebulk voltage V_(BB) and the negative word voltage V_(NEG) exceeds normaloperating conditions, the single pump can supply the necessary power.Further, the supply regulation circuit 212 according to the presentembodiment prevents the negative word voltage V_(NEG) from becoming morenegative than the bulk voltage V_(BB), which might otherwise lead to alatchup problem.

A supply regulation circuit according to various aspects of the presentinvention may also comprise a compensator circuit to compensate for anyextra current or other operational requirement of the regulated voltage.For example, the compensator circuit may be connected to the negativeword voltage V_(NEG) to compensate for leakage current in the transistor416. The compensator circuit may be configured in any suitable manner tocompensate for the leakage current.

For example, referring to FIG. 6, the compensator circuit may include acurrent source 610 connected to the source of the transistor 416. Thecurrent source 610 may provide a relatively low current to the regulatedvoltage to compensate for current lost as leakage or stand-by current.In the present embodiment, the current source 610 inhibits the negativeword voltage V_(NEG) from becoming more negative than the controlreference voltage. The current source 610 may be implemented in anysuitable manner, such as using a conventional current mirror circuit tomaintain a desired current through the transistor 416.

In an alternative embodiment, the compensator circuit may be configuredto compare the regulated voltage to the reference voltage and compensateif the regulated voltage is too low. For example, referring to FIG. 7,an alternative compensator circuit according to various aspects of thepresent invention suitably comprises a second differential amplifier 710and a second transistor 712. The second differential amplifier 710 has anoninverting input connected to the control reference voltage and aninverting input connected to the negative word line voltage V_(NEG).Like the first differential amplifier 414, the second differentialamplifier 710 generates a differential signal proportional to thedifference between the control reference voltage and the negative wordline voltage V_(NEG), which is suitably provided to a second impedance,such as the n-channel transistor 712.

The second transistor 712 is suitably configured to modulate theimpedance between a more positive voltage level, such as ground, and thenegative word line voltage V_(NEG) according to the second differentialsignal generated by the second differential amplifier 710. In thepresent embodiment, the gate of the second transistor 712 is connectedto the second differential output, and the source and drain of thesecond transistor 712 are suitably connected to ground and the source ofthe first transistor 416, respectively. The second transistor 712 may beconfigured to exhibit additional resistance or may be connected to anadditional resistor to increase the resistance of the compensationcircuit. The negative word line voltage V_(NEG) is provided at the nodebetween the first impedance 416 and the second impedance 712. Thus, thefirst differential amplifier and transistor pair 414, 416 tends to pullthe negative word line voltage V_(NEG) to the control reference voltageif the negative word line voltage is too high, and the seconddifferential amplifier and transistor pair 710, 712 tends to pull thenegative word line voltage V_(NEG) to the control reference voltage ifthe regulated voltage is too low.

The present invention is described with reference to various preferredembodiments. However, changes and modifications may be made to variousexemplary embodiments without departing from the scope of the presentinvention. These and other changes or modifications are intended to beincluded within the scope of the present invention as set forth in theappended claims.

1. An electronic system, comprising: a supply configured to provide afirst voltage; and a supply regulation circuit configured to provide aregulated voltage, comprising: a control circuit configured to generatea control signal according to the magnitude of the control referencevoltage; and an adjustment circuit configured to receive the controlsignal and adjust the regulated voltage according to the control signal.2. An electronic system according to claim 1, wherein the controlcircuit is configured to: compare the magnitude of the control referencevoltage to a magnitude of the regulated voltage; and generate thecontrol signal according to the comparison of the magnitude of thecontrol reference voltage to the magnitude of the regulated voltage. 3.An electronic system according to claim 1, wherein the control circuitincludes an amplifier with a gain of approximately unity.
 4. Anelectronic system according to claim 1, wherein the control circuitincludes a differential amplifier, including: a first input connected tothe control reference voltage; a second input connected to the regulatedvoltage; and a control signal output connected to the adjustmentcircuit.
 5. An electronic system according to claim 1, wherein theadjustment circuit comprises an impedance having an adjustable impedancevalue responsive to the control circuit, and wherein the regulatedvoltage corresponds to the adjustable impedance value.
 6. An electronicsystem according to claim 1, wherein the adjustable impedance comprisesa transistor, comprising: a first terminal connected to the regulatedvoltage; a second terminal connected to a reference potential; and acontrol terminal connected to the control signal.
 7. An electronicsystem according to claim 1, further comprising a compensator circuitconfigured to provide a current to the adjustment circuit.
 8. A memorysystem according to claim 1, wherein the first voltage is a bulkvoltage.